"We have instructed our Ambassador Carlos Vecchio to meet immediately with the Southern Command and the admiral so we can establish direct relations in matters of cooperation," Efe news quoted the opposition leader as saying to a gathering in an east Caracas plaza on Saturday.

He repeated that with the backing of allied governments led by the US, "all options remain on the table" to resolve the national crisis, and that includes, he said, Nicolas Maduro stepping down from power, given that Guaido considers his presidency illegitimate. Guaido said the opposition also seeks to "apply the necessary pressure" to end the so-called Bolivarian Revolution, in power since 1999.

"At all times I have spoken of cooperation, because intervention in Venezuela already exists," he said in denouncing the supposed participation of Cubans in the Bolivarian National Armed Forces (FANB) and the presence in the country of the Colombian National Liberation Army (ELN) guerrilla group.

"When invited by @jguaido & the legitimate government of #Venezuela, I look forward to discussing how we can support the future role of those @ArmadaFANB leaders who make the right decision, put the Venezuela people first & restore constitutional order," he said.

"About the possibility or not of military cooperation on Venezuelan soil...and whether it will be required or not, some would say, and I would say, that we crossed the red line some time ago," he later told a press conference, adding that "the emergency" in the country "is obvious."

"Listen to the word I used - military cooperation on Venezuelan soil, not intervention. Why? Because intervention already exists - the Cuban military operating intelligence and counterintelligence in Venezuela, the Russian military," he added.

Venezuela has been going through a time of high political tension since last January, when Maduro was sworn into another six-year term in office that is neither recognised by the opposition nor by part of the international community. In response, Guaido proclaimed himself interim president of the nation, after which he was recognised as such by more tha 50 countries, headed by the US.